Zone flower planting times guide
The fine art of orchestrating blooms
One of the best tools for determining which plants may thrive in a given climate and when to start different flowering plants is the United States Department of Agriculture’s map of planting zones. This helpful guide illustrates average low temperatures all across the United States. The U.S.D.A. has compiled data for 60 years to make the maps we use today. This depth of data makes the map both reliable and extremely useful. The U.S.D.A planting zones map provides information for large swaths across the country, and even for smaller microclimates, in some cases. These subdivisions act as a starting point for the garden planner and describe planting times for flowers and other garden mainstays.
Timing is everything
Most of the plants that we use as flowering ornamentals in the garden can be broken into three broad categories: bulbs, annuals, and perennials. In the most general sense, each of these categories of flowering plants has a season, which is an optimal time for planting:
- Bulbs that flower from early to late spring should be planted in the fall. Exactly when to plant can be determined in part by one’s planting zone. In general, the colder the climate the earlier the fall planting date. Some bulbs that bloom in the summer need to be planted later. Many of those bulbs and tubers that produce summer’s floral bounty are vulnerable to frost; these plants die when temperatures drop below freezing. In northern and very moist winter climates, these bulbs should be planted after the threat of winter rain and deep frost has passed.
- Annuals, like the frost-tender summer flowering bulbs, can only survive and thrive in the balmy temperatures of summer. While annuals put on their shows from late May to frost in many of the U.S.D.A.’s planting zones, they too have a preference for specific planting times. In any climate, they should be planted as soon as the threat of frost has passed and before hot summer temperatures. Depending on one’s planting zone, this could be February to May. In fact, some warm climates support annual planting all winter long. The later annuals are planted, the less time they have to produce blooms and foliage and the more likely they are to be stressed by punishing summer heat and drought.
- The most forgiving of the flowering plant categories are the perennials. Flowering perennials can be planted in a variety of seasons with good results. The prevailing wisdom is to plant these hardy flowers in the fall when cool weather and moist conditions make for easy root transitions from pot to ground. Despite this, fall “sweet spot” perennials can do just as well when planted in spring, as soon as the soil is workable. Finally, for those of us seduced by the garden center’s high season displays, perennials can even be planted in the summer. When plating in the summer, the gardener must take extra care to make the plants transition from the pampered nursery conditions to the wild of the garden as smooth as possible. Some ways to ease this difficult transition are to plant in the cooler evening or early morning temperatures, keep the plant mulched and watered, and to give the plant the best soil conditions possible.
No matter which zone a gardener lives in and what type of flowering plants they enjoy, timing in planting can mean the difference between breathtaking success and unfortunate failure. A careful examination of a map of planting zones and an understanding of the conditions in an individual’s area are the best first steps in timing the planting of a bountiful flowering garden.
